JINDO, South Korea — The parents waited in dread through the night, huddled under blankets in this South Korean port town, staring out to sea for a sign that rescuers had found any of the 281 people, many of them high school students, still missing after a ferry sank on Wednesday.
They refused to sleep in a tent set up for them, preferring to scan the horizon for helicopters returning from the rescue effort 11 miles off the country’s southwest coast. As the hours passed with little news of what may be one of South Korea’s worst peacetime disasters, they demanded information from officials who said that fierce tides were keeping divers from entering the ship, which had mostly slipped beneath the waves long before.
“Why are you not going in to save them?” one woman screamed. Another, Chung Hae-sook, the mother of a missing 16-year-old boy, echoed her rage: “There is no tomorrow for this,” she said. “My heart is turning to ashes.”
By Thursday morning, the Ministry of Security and Public Administration, which is coordinating the rescue efforts, reported that 175 passengers and crew members had been rescued. Nine people were confirmed dead, including four students, two teachers and a member of the ferry’s crew. But fears of a much higher death toll were stoked as survivors said they believed that many people had been trapped below deck. According to some who spoke to the local news media, passengers had been told to remain in their seats and may have stayed there until it was too late.
“People were shouting, ‘Break the windows,’ but the water came up too quickly and many could not come outside,” Kim Seong-muk, a rescued passenger, told the television station YTN.
Survivors reported hearing a loud noise and feeling a jolt before the ship, the Sewol, began to list and sink.
Of the 462 people aboard, 325 were students from Danwon High School in Ansan, about 20 miles south of Seoul. By midnight, about 75 of the students had been rescued. They had been on an overnight voyage to Jeju, a popular resort island, where they were scheduled for a four-day field trip and sightseeing.
The students, in their second year of high school, were taking the trip as a break before their last year, when they must take difficult college entrance exams.
One of the students who made it out, Kim Tae-young, said he had seen people in the ferry’s cafeteria and in a game room on a level below him before the ship started listing.
“The water rushed in, up to my neck, and it was difficult to climb to the top of the boat because it was badly tilted,” he told News Y, a cable channel. “I saw shipping containers tossed off the ship’s deck and floating in the water. I also saw a vending machine toppled and two girls trapped under it.”
The cause of the accident was not immediately clear. By nightfall, no South Korean official or analyst had raised the possibility of foul play by North Korea, which was accused of sinking a South Korean Navy ship with a torpedo in 2010, a charge the North denied.
During a brief news conference on Wednesday, Kim Young-bung, an executive at the Cheonghaejin Marine Company, which operated the ship, offered the company’s “deepest apology” but few details about what had happened.
The maritime police said they were questioning the ship’s captain, Lee Jun-seok, 69, and other surviving crew members while arranging for cranes to be sent to the scene, in the Yellow Sea, to try to lift the vessel.
The 6,825-ton ferry had been sailing from Incheon, a port west of Seoul, to Jeju, roughly 60 miles off the southern coast of South Korea, when it sent a distress signal on Wednesday morning. Video showed rescuers scaling the side of the listing ship, pulling out survivors and placing them in baskets lowered by helicopters.
YTN quoted surviving students describing a chaotic scene in which passengers tripped and bumped into one another and luggage was tossed about as the ship leaned precariously. People jumped into the water in life jackets and swam to fishing boats that had arrived near the sinking ship, they said. The passengers were wrapped in blankets and taken to shelters and hospitals in nearby ports.
In a text message shown on the station’s broadcast, a student had written, “Dad, I can’t walk out because the ship is tilted too much, and I don’t see anyone in the corridor.” It was unclear if the student survived.
On Wednesday, President Park Geun-hye declared, “We must not give up.”
Speaking at the headquarters of the Ministry of Security and Public Administration, she said, “We must do our best to rescue even one of those passengers and students who may not have escaped from the ship.”
Lee Gyeong-og, vice minister of security and public administration, said that 160 navy and coast guard divers were working at the scene, but that their operations were being hampered by rapid currents and poor underwater visibility.
Around 4 a.m. on Thursday, a Coast Guard official in Jindo told parents that divers had conducted five searches so far but were waiting for better conditions before heading back down. The sea off western South Korea has strong tides.
Of those confirmed dead, one was a 27-year-old female crew member found dead in the water and another was a male student who died at a hospital. Rescuers later found at least two more students from the Ansan school who had died.
South Korea has not had a major ferry accident in two decades. The last was in 1994, when a tourist ferry caught fire on a lake, killing 30 people. A year earlier, 292 people died when an overloaded ferry, sailing despite warnings of bad weather, sank off the country’s west coast.
On Wednesday, Mr. Lee of the security ministry declined to comment on the likelihood of finding more survivors. The ship sank in waters 104 feet deep, and the water temperature in the area was about 54 degrees Fahrenheit, cold enough to cause hypothermia after about two hours, officials said.
The ship’s departure from Incheon on Tuesday evening was delayed by two hours because of heavy fog, officials said. It was also carrying 150 cars and trucks, below its capacity of 180.
Mrs. Chung — the woman who was waiting in Jindo for news of her 16-year-old son, Park Sung-ho — said he had sent her a text message on Tuesday saying the ferry might not leave the dock, but later messaged her that it was departing and that he would return safely.
“I feel like the parents, including myself, are here waiting for our children to die,” she said.
Kim Dong-soo, a truck driver who was on the Sewol and said he frequently took the ferry to Jeju, told News Y that the ship had begun leaning sharply after it made a sharp turn to the right. It was also sailing much closer to the coast than it usually does, he said.
“I wonder why the rescuers who first got to the ship didn’t do anything about those 100 or 200 I think were trapped inside the ship,” he said. “They were just picking up those already on the top of the ship.”
The ferry, built in Japan in 1994 and operated by Cheonghaejin Marine since late 2012, could hold 920 passengers.
For the parents waiting in the morning chill in Jindo, the day had been a roller-coaster ride of emotions. Soon after the accident, the ministry had given a much lower estimate of the number of missing, an error it attributed to confusing reports from the scene.
Mrs. Chung said the school had also sent a message saying the students were all being rescued.
Her younger brother, who was keeping vigil with her, said he was “ashamed” of the government for not doing more.
“How can we trust them?” he said. “It feels like the divers are not going into the water lest they die. How can we trust the authorities if a war breaks out?”
Another relative of a missing child sounded resigned. “I don’t have much hope at this point,” said Choi Dae-gwang, whose son Choi Su-bin, 17, was missing. But “they should at least pretend to rescue people.”